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++ // Copyright (C) 2026 The Qt Company Ltd.
++ // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only
++
++ import QtQuick
++ import QtQuick3D
++
++ /*!
++ \qmltype ProceduralSkyMaterial
++ \inqmlmodule QtQuick3D.Helpers
++ \since 6.13
++ \brief A gradient-based sky material compatible with ProceduralSkyTextureData.
++
++ ProceduralSkyMaterial is a GPU-based sky rendered via \l SkyMaterial that
++ provides the same gradient-and-sun-disk sky model as \l ProceduralSkyTextureData,
++ but with real-time updates and no CPU texture baking.
++
++ It can be used as a drop-in replacement for ProceduralSkyTextureData: set
++ \l{SceneEnvironment::backgroundMode}{backgroundMode} to
++ \c SceneEnvironment.SkyMaterial and assign this type to
++ \l{SceneEnvironment::skyMaterial}{skyMaterial} instead of using a Texture
++ with ProceduralSkyTextureData as its texture data.
++
++ \section1 Example Usage
++
++ \qml
++ import QtQuick3D
++ import QtQuick3D.Helpers
++
++ View3D {
++ environment: SceneEnvironment {
++ backgroundMode: SceneEnvironment.SkyMaterial
++ skyMaterial: ProceduralSkyMaterial {
++ sunLatitude: 35
++ sunLongitude: 45
++ skyTopColor: "#1a3a6a"
++ }
++ }
++ }
++ \endqml
++
++ \sa ProceduralSkyTextureData, SkyMaterial
++ */
++ SkyMaterial {
++ fragmentShader: Qt.resolvedUrl("proceduralsky.frag")
++ iblSampleCount: 256
++ radianceMapSize: 256
++
++ /*!
++ \qmlproperty color ProceduralSkyMaterial::skyTopColor
++ \since 6.13
++ \default "#A5D6F1"
++ The color at the top of the sky dome.
++ */
++ property color skyTopColor: "#A5D6F1"
++
++ /*!
++ \qmlproperty color ProceduralSkyMaterial::skyHorizonColor
++ \since 6.13
++ \default "#D6EAFA"
++ The color of the sky at the horizon.
++ */
++ property color skyHorizonColor: "#D6EAFA"
++
++ /*!
++ \qmlproperty real ProceduralSkyMaterial::skyCurve
++ \since 6.13
++ \default 0.09
++ Controls the curvature of the sky gradient blend from horizon to top.
++ Values below 1 curve toward the horizon, values above 1 toward the top.
++ */
++ property real skyCurve: 0.09
++
++ /*!
++ \qmlproperty real ProceduralSkyMaterial::skyEnergy
++ \since 6.13
++ \default 1.0
++ Brightness multiplier for the sky hemisphere.
++ */
++ property real skyEnergy: 1.0
++
++ /*!
++ \qmlproperty color ProceduralSkyMaterial::groundBottomColor
++ \since 6.13
++ \default "#282F36"
++ The color at the bottom of the ground hemisphere.
++ */
++ property color groundBottomColor: "#282F36"
++
++ /*!
++ \qmlproperty color ProceduralSkyMaterial::groundHorizonColor
++ \since 6.13
++ \default "#6C655F"
++ The color of the ground at the horizon.
++ */
++ property color groundHorizonColor: "#6C655F"
++
++ /*!
++ \qmlproperty real ProceduralSkyMaterial::groundCurve
++ \since 6.13
++ \default 0.02
++ Controls the curvature of the ground gradient blend from horizon to bottom.
++ */
++ property real groundCurve: 0.02
++
++ /*!
++ \qmlproperty real ProceduralSkyMaterial::groundEnergy
++ \since 6.13
++ \default 1.0
++ Brightness multiplier for the ground hemisphere.
++ */
++ property real groundEnergy: 1.0
++
++ /*!
++ \qmlproperty color ProceduralSkyMaterial::sunColor
++ \since 6.13
++ \default "#ffffff"
++ The color of the sun disk.
++ */
++ property color sunColor: "#ffffff"
++
++ /*!
++ \qmlproperty real ProceduralSkyMaterial::sunLatitude
++ \since 6.13
++ \default 35.0
++ The elevation of the sun above the horizon in degrees. 0 places the sun on
++ the horizon; 90 places it directly overhead.
++ */
++ property real sunLatitude: 35.0
++
++ /*!
++ \qmlproperty real ProceduralSkyMaterial::sunLongitude
++ \since 6.13
++ \default 0.0
++ The horizontal rotation of the sun around the vertical axis in degrees.
++ */
++ property real sunLongitude: 0.0
++
++ /*!
++ \qmlproperty real ProceduralSkyMaterial::sunAngleMin
++ \since 6.13
++ \default 1.0
++ The angular radius of the solid sun disk in degrees.
++ */
++ property real sunAngleMin: 1.0
++
++ /*!
++ \qmlproperty real ProceduralSkyMaterial::sunAngleMax
++ \since 6.13
++ \default 100.0
++ The outer angular radius of the sun halo in degrees.
++ The halo fades out from \l sunAngleMin to this value.
++ */
++ property real sunAngleMax: 100.0
++
++ /*!
++ \qmlproperty real ProceduralSkyMaterial::sunCurve
++ \since 6.13
++ \default 0.05
++ Controls the falloff curve of the sun halo between \l sunAngleMin and
++ \l sunAngleMax. Values below 1 produce a sharp-edged halo; values above
++ 1 produce a soft glow.
++ */
++ property real sunCurve: 0.05
++
++ /*!
++ \qmlproperty real ProceduralSkyMaterial::sunEnergy
++ \since 6.13
++ \default 1.0
++ Brightness multiplier for the sun disk and halo.
++ */
++ property real sunEnergy: 1.0
++
++ // Computed sun direction passed as vec3 uniform to the shader.
++ // Matches the visual output of ProceduralSkyTextureData used as a SkyBox lightProbe.
++ readonly property vector3d sunDirection: {
++ const latRad = sunLatitude * Math.PI / 180.0
++ const lonRad = sunLongitude * Math.PI / 180.0
++ return Qt.vector3d(
++ -Math.cos(lonRad) * Math.cos(latRad),
++ Math.sin(latRad),
++ -Math.sin(lonRad) * Math.cos(latRad)
++ )
++ }
++ }